Allegri slams Juventus defending in Barcelona loss

Massimiliano Allegri bemoaned a collapse in the defensive standards that humbled Barcelona five months ago following Juventus' 3-0 Champions League Group D defeat at Camp Nou.

Juve shut out Barca over the course of 180 minutes as they triumphed 3-0 on aggregate in last season's quarter-final between the sides, but the LaLiga leaders found their Serie A counterparts a far less robust proposition this time around.

A brilliant Lionel Messi goal put the hosts in front towards the end of a first half as even as the second period was one-sided.

Messi created Ivan Rakitic's goal and helped himself to another as a Juve defence without the injured Giorgio Chiellini and still adjusting to life without Leonardo Bonucci provided increasingly flimsy resistance.

"We played a good first half but when you play these kind of games you have to take your chances," Allegri told reporters.

"We didn't and we were punished at the end of the first half. Ironically we conceded three goals from counter-attacks but this was our worst mistake because we had to remain compact after Barcelona's goal.

"Obviously they have this player who can change every game but we had to do better in the second half.

"You cannot expect to come here and dominate the game so we have to play better at a mental level, always trying to remain in the game even when everything seems difficult.